Variable area nozzle for turbines or compressors

ABSTRACT

A variable area nozzle assembly arranged in an annular housing adjacent a rotor. In order to accurately position movable vanes in the nozzle while compensating for the effects of wear or heat distortion in the nozzle assembly, bevel bears are secured to the vanes and intermediate bevel gears are arranged therebetween with springs axially urging the gears into positive engagement with each other.

United States Patent [191 Davis March 6, 1973 VARIABLE AREA NOZZLE FOR TURBINES OR COMPRESSORS 3,025,036 3/1962 Kumm et al. ..4l5/23 FOREIGN PATENTS OR APPLICATIONS 601,828 5/1948 Great Britain ..415/160 380,701 9/1932 Great Britain ..4l5/163 Primary ExaminerI-lenry F. Raduazo Att0rney-Fryer, Tjensvold, Feix, Phillips & Lempio [57] ABSTRACT A variable area nozzle assembly arranged in an annular housing adjacent a rotor. In order to accurately position movable vanes in the nozzle while compensating for the effects of wear or heat distortion in the nozzle assembly, bevel bears are secured to the vanes [56] References Cited and intermediate bevel gears are arranged therebetween with springs axially urging the gears into UNITED STATES PATENTS positive engagement with each other.

3,327,933 6/1967 Baumann et a1 ..415/150 6 Claims, 3 Drawing Figures l7 2i 7 l 7 VARIABLE AREA NOZZLE FOR TURBINES OR COMPRESSORS The present invention relates to variable area nozzles of the type employed with either a turbine or compressor rotor and more particularly to such a nozzle assembly including intermeshing bevel gears for positively positioning the vanes.

Variable area nozzles are known in the priorart, for example, in gas turbine engines to improve efficiency over relatively wide ranges of operating speeds. In such nozzle assemblies, it is necessary to accurately position each of the movable vanes and to maintain them in the selected position during operation of the turbine or rotor. Such accuracy is difficult to maintain, for example, due to excessive tolerances arising in a drive arrangement for positioning the vanes or to distortion caused by the flow of hot gases through the nozzle.

One exemplary prior art arrangement for controlling movable vanes in a variable area nozzle employed a ring gear arranged about the vanes with the ring gear being operable to position the vanes. Such arrangements have not been found completely satisfactory particularly in combination with turbine rotors, for example, because of the particular susceptibility of the ring gear to heat distortion.

Accordingly, it is an object of the present invention to provide a variable area nozzle assembly including means for accurately positioning movable vanes in the nozzle.

It is a further object of the invention to provide such a variable area nozzle wherein the positions of the movable vanes are controlled by bevel gears with compensating means for maintaining the gears in positive engagement and thus reducing or eliminating the problem of backlash within the meshing arrangement of gears.

Other objects and advantages of the present invention are made apparent in the following description having reference to the accompanying drawing.

In the drawing:

FIG. 1 is a fragmentary sectioned view of a variable area nozzle constructed according to the present invention;

FIG. 2 is a radially sectioned view of the variable area nozzle illustrated in conjunction with a portion of a rotor; and

FIG. 3 is a fragmentary sectioned view of a portion of a variable area nozzle assembly including compensating spring means.

The variable area nozzle of the present invention is described below within the preferred environment of a gas turbine engine which is partially illustrated in the drawing. Referring to FIG. 1 and particularly to FIG. 2, a variable area nozzle assembly indicated at 11 is arranged in axial alignment with a bladed turbine rotor 12. An outer annular housing portion 13 and a hub portion 14 of the housing form an annular passage 16 through which gas flows for interaction with the nozzle and turbine rotor.

The nozzle assembly includes a plurality of movable vanes 17 journal mounted in the hub 14 by means of bushings such as that indicated at 18 in FIG. 2. An end portion 19 of each vane is similarly mounted in a stepped bore 21 formed by the housing portion 13. A radially inwardly beveled drive gear 22 is secured to the protruding end portion 19 of each vane by means of a nut 23 threadedly engaging the end portion of the vane.

single operating gear 26 is arranged in meshing relation with one pair of the drive gears. Each of the spacer gears 24 is mounted for rotation on a stub shaft 27 by means of a bushing 28. The stub shafts are secured, for example, by press fit into bores 29 formed in the housing portion 13. The spacer gears are also maintained on the shafts 27 by means of threaded nuts 31.

A cover 32 provides protection for the gears arranged outwardly of the housing portion 13. A shaft 33 for the operating gear 26 extends outwardly through the cover 32 and may be rotated by means such as a lever (not shown) to operate the drive gears 22 and position the vanes 17. The spacer gears 24 also provide for rotation of each of the vanes in a similar direction.

As may be best seen, the threaded nuts 23 urge the drive gears 22 radially inwardly to maintain positive engagement between the drive gears 22 and spacer gears 24. The nuts 23 may be adjusted to compensate for wear in the gears, thus maintaining them in positive engagement and tending to minimize or eliminate backlash.

The vane 17 and drive gear 22' of FIG. 3 also have a spring 41 which tends to constantly compensate for gear wear and thermal distortion arising during operation of the turbine engine. Such a spring 41 is arranged in an annular space between the housing portion 13' and each end portion 19' to act radially inwardly on the vanes 17 by means of a bushing 42. Thus, the drive gears 22' are urged radially inwardly into positive engagement with the spacer gears. (also see FIG. 1.)

Similar springs could also be arranged to urge the spacer gears radially outwardly and thereby constantly compensate for gear wear.

What is claimed is:

1. A movable vane assembly of the type used in conjunction with a turbine or compressor rotor for interaction with a gas stream, comprising a plurality of radially aligned vanes circumferentially arranged within an annular passage formed by a housing, the vanes being supported for rotation about their radial axes to vary the effective crosssection area of the annular passage,

a plurality of rotatable bevel gears circumferentially arranged upon the housing, alternate gears being coupled for driving the respective vanes in rotation, the intermediate gears occupying spaces between the drive gears and providing for rotation of the drive gears and vanes in a common direction of rotation,

operating means effectively coupled with the gears for selectively controlling the rotational positions of the vanes, and

compensating means acting axially on at least a portion of the gears for maintaining the gears in positive engagement with each other.

2. The movable vane assembly of claim 1 wherein the vanes are journal mounted in an annular portion and a hub portion of the housing, end portions of the vanes extending through the annular housing portion for connection with the drive gears, the intermediate gears also being journal mounted in the annular housing.

3. The movable vane assembly of claim 2 wherein the drive gears have beveled gear teeth and the intermediate gears have mating beveled gear teeth, the compensating means comprising springs arranged for interaction between the annular housing portion and the end portions of the vanes.

4. The movable vane assembly of claim 3 wherein the operating means comprises an operating gear arranged in meshing relation with two of the drive gears and actuator means coupled with the operating gear.

5. The movable vane assembly of claim 1 wherein the compensating means are arranged for axial interaction 

1. A movable vane assembly of the type used in conjunction with a turbine or compressor rotor for interaction with a gas stream, comprising a plurality of radially aligned vanes circumferentially arranged within an annular passage formed by a housing, the vanes being supported for rotation about their radial axes to vary the effective cross-section area of the annular passage, a plurality of rotatable bevel gears circumferentially arranged upon the housing, alternate gears being coupled for driving the respective vanes in rotation, the intermediate gears occupying spaces between the drive gears and providing for rotation of the drive gears and vanes in a common direction of rotation, operating means effectively coupled with the gears for selectively controlling the rotational positions of the vanes, and compensating means acting axially on at least a portion of the gears for maintaining the gears in positive engagement with each other.
 1. A movable vane assembly of the type used in conjunction with a turbine or compressor rotor for interaction with a gas stream, comprising a plurality of radially aligned vanes circumferentially arranged within an annular passage formed by a housing, the vanes being supported for rotation about their radial axes to vary the effective cross-section area of the annular passage, a plurality of rotatable bevel gears circumferentially arranged upon the housing, alternate gears being coupled for driving the respective vanes in rotation, the intermediate gears occupying spaces between the drive gears and providing for rotation of the drive gears and vanes in a common direction of rotation, operating means effectively coupled with the gears for selectively controlling the rotational positions of the vanes, and compensating means acting axially on at least a portion of the gears for maintaining the gears in positive engagement with each other.
 2. The movable vane assembly of claim 1 wherein the vanes are journal mounted in an annular portion and a hub portion of the housing, end portions of the vanes extending through the annular housing portion for connection with the drive gears, the intermediate gears also being journal mounted in the annular housing.
 3. The movable vane assembly of claim 2 wherein the drive gears have beveled gear teeth and the intermediate gears have mating beveled gear teeth, the compensating means comprising springs arranged for interaction between the annular housing portion and the end portions of the vanes.
 4. The movable vane assembly of claim 3 wherein the operating means comprises an operating gear arranged in meshing relation with two of the drive gears and actuator means coupled with the operating gear.
 5. The movable vane assembly of claim 1 wherein the compensating means are arranged for axial interaction with alternate ones of the gears, the compensating means being effectIve to urge the alternate gears against the remaining gears and thus provide for positive engagement between all of the plurality of gears. 